| tension | 1. The act of stretching. 2. The condition of being stretched or strained, the degree to which anything is stretched or strained. 3. <physics> Voltage. 4. <chemistry> The partial pressure of a gas in a fluid, for example, of oxygen in blood. Origin: L. Tensio, Gr. Tonos (13 Jan 1998) |
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| tension, arterial | The pressure of the blood within an artery, the arterial pressure. Also called the intra-arterial pressure. (12 Dec 1998) |
| tension curve | The direction of the trabeculae in cancellous bone tissue adapted to resist stress. (05 Mar 2000) |
| tension headache | <neurology> A benign form of headache that results from the painful spasm (muscle tightness) and inflammation of muscles of the head and neck. Tension headache is one of the most common forms of headache. Spasm and contraction of the head and neck muscles may occur in response to fatigue, overuse, eye strain, excessive smoking, stress, anxiety or depression. Sleeping in an abnormal position or prolonged work involving immobilisation of the neck in one position (typing, computers, etc.) are considered common triggers. Exercising and stretching the muscles of the head and neck can reduce the occurrence of muscle tension headaches. (13 Jan 1998) |
| tension, intraocular | The pressure within the eye. (12 Dec 1998) |
| tension, intravenous | The pressure of the blood within a vein, the venous pressure. (12 Dec 1998) |
| tension pneumothorax | A variety of spontaneous pneumothorax in which air enters the pleural cavity and is trapped during expiration; intrathoracic pressure builds to values higher than atmospheric pressure, compresses the lung, and may displace the mediastinum and its structures toward the opposite side, with consequent disadvantageous effects on blood flow. Synonym: pressure pneumothorax, valvular pneumothorax. (05 Mar 2000) |
| tension suture | <surgery> A heavy reinforcing suture placed deep within the muscles and fasciae of the abdominal wall to relieve tension on the primary suture line and thus obviate postoperative wound disruption. Synonym: tension suture. (05 Mar 2000) |
| tissue tension | A theoretical condition of equilibrium or balance between the tissues and cells whereby overaction of any part is restrained by the pull of the mass. (05 Mar 2000) |
| low tension glaucoma | Optic nerve atrophy and excavation with typical field defects of glaucoma but without abnormal increase in intraocular pressure. (05 Mar 2000) |
| Abbe test plate | <equipment> A long, wedge-shaped coverslip about 0.20 mm thick at one end and 0.10 to 0.12 mm at the other end coated chemically with a silver film on which are ruled horizontal lines. at each variation in thickness of 0.01 mm there are vertical lines. By means of oblique illumination and by focusing on different portions of the plate, it is possible to determine the optimum coverslip thickness for any objective and also, for microscopes with drawtubes, the tube length for best objective performance. The approximate freedom from spherical and chromatic aberrations can also be estimated. Small isolated bits of silver near the edges of the lines form good objects for the star test (05 Aug 1998) |
| acetone test | A test for ketonuria; the suspected urine is shaken up with a few drops of sodium nitroprusside, and strong ammonia water is then gently poured over the mixture; if acetone is present, a magenta ring forms at the line of contact; tablets containing sodium nitroprusside and alkali are now more commonly used. (05 Mar 2000) |
| achievement test | A standardised test used to measure acquired learning, e.g., competence in a specific subject area such as reading or arithmetic, in contrast to an intelligence test which is a useful index of potential ability or learning. (05 Mar 2000) |
| acidified serum test | Lysis of the patient's red cells in acidified fresh serum, specific for paroxysmal nocturnal haemoglobinuria. Synonym: Ham's test. (05 Mar 2000) |
| acid loading test | <nephrology> This is a test used in the diagnosis of renal tubular acidosis. The patient takes ammonium chloride capsules for 3 days to acidify the blood (lower blood pH). A sample of the urine and the blood is then collected and the results are interpreted. (27 Sep 1997) |